FIBRINOGEN RECEPTOR ANTAGONIST

PURPOSE: To prepare the subject antagonist, comprising a cyclic polypeptide containing a tripeptide sequence Arg-Gly-Asp and having a relatively short duration of activities suitable for therapeutic treatment in which the prevention of blood platelet aggregation over a short period of time is desired. CONSTITUTION: This firbinogen receptor antagonist comprises a cyclic polypeptide represented by formula I (A is H, an acylamido, an aminoacylamido, etc.; R and R are each H, CH3 , C2 H5 or a 1-5C alkyl; X-Y is S-S, CH2 -S, S-CH2 , CH2 CH2 , etc.; F is an L-amino acid of tryptophan, phenylalanine, leucine, etc.; G is a D- or an L-amino acid, a cyclic secondary amino acid, etc.; D is an L-isomer of homoarginine, guanidoamino acid, etc.; E is H, COOH, CONH2 , formula II, etc.; R is H or CH3 ), preferably a polypeptide represented by formula III to V. The antagonist is used for promoting the thrombolysis and preventing the reocclusion.